Climate-readiness of fishery management procedures with application to the southeast US AtlanticPeterson, Cassidy D; Klibansky, Nikolai; Vincent, Matthew T; Walter, John F
doi: 10.1093/icesjms/fsae154pmid: N/A
Global climate change threatens the assumption of stationarity inherent in many fisheries management decisions. This heightens the importance of developing management strategies that are robust to future uncertainty. Management strategy evaluation (MSE) is a framework in which management procedures (MPs) can be developed and tested using closed-loop simulation. We explored the performance of various model-based and empirical MPs with nonstationary future projections for three commercially and recreationally important fish stocks in the southeast US Atlantic. Using openMSE, we tested candidate MP performance across projections designed to emulate plausible future conditions, including regime shifts, nonstationarity, and observation error shifts in the survey index. Candidate MP performance was primarily measured based on its ability to maintain a healthy stock biomass. Results of this MSE demonstrate that several empirical MPs may be better able to adapt to regime shifts and nonstationary dynamics compared to traditional model-based MPs that employ full age-structured stock assessments, though empirical MPs struggle to maintain stock biomass when facing artificial index observation error shifts. Relative performance of model-based versus empirical MPs varied by stock and climate-change scenario. These findings highlight the value that adaptive MPs may hold for climate-ready fisheries management.
Scoping an Integrated Ecosystem Assessment for the southern Benguela: fisheries still biggest riskBornman, Eugin; Shannon, Lynne; Jarre, Astrid
doi: 10.1093/icesjms/fsae018pmid: N/A
The southern Benguela ecosystem faces complex pressures from anthropogenic activities and climate change, leading to structural and functional changes. To counter ecosystem service losses, intergovernmental marine science organizations propose integrated management. However, predictions to evaluate alternative strategies are challenging due to multifaceted sector interactions affecting ecological components. Scoping phases of Integrated Ecosystem Assessments (IEA), such as the Options for Delivering Ecosystem-Based Marine Management (ODEMM), identify priority sectors and pressures for management using linkage chains and impact risk scores. This study expands a South African-wide ODEMM assessment to investigate dependent sectors in the southern Benguela. Fishing emerged as the primary sector, exhibiting high connectance and impact risk on ecological components. Disaggregation of the fishing sector into sub-sectors and over three 21-year time periods revealed the demersal trawl and mixed species inshore trawl sectors to still have the greatest impact despite recent mitigation efforts, driven by species extraction, bycatch, and ‘incidental loss’. Research gaps, such as the effects of recreational fisheries and underwater noise, were identified and need to be addressed to improve future ecosystem assessments. Additionally, the effects of climate on long-term, ecosystem-scale variability and change need more attention in IEAs and should be incorporated into frameworks such as ODEMM.
Poor performance of regime shift detection methods in marine ecosystemsHaines, Hannah; Planque, Benjamin; Buttay, Lucie
doi: 10.1093/icesjms/fsae103pmid: N/A
Regime shifts have been reported as ubiquitous features across the world’s oceans. Many regime shift detection methods are available, but their performance is rarely evaluated, and the supporting evidence for regime shifts may be thin because of the nature of marine ecological time series that are often short, autocorrelated, and uncertain. In the Norwegian Sea, a regime shift has been reported to have occurred in the mid-2000s, with simultaneous changes in oceanography, plankton, and fish. Here, we evaluate the evidence for this regime shift using four commonly used regime shift detection methods (Strucchange, STARS, EnvCpt, and Chronological Clustering) on 32 annual time series that describe the main components of the Norwegian Sea ecosystem, from hydrography and primary production up to fish population metrics. We quantify the performance of each method by measuring its false-positive rate, i.e. the proportion of times the method detects a regime shift that was not present in simulated control time series. Our results show that all methods have high to very high false-positive rates. This challenges the evidence for a regime shift in the Norwegian Sea and questions earlier reviews of regime shifts across the world’s oceans.
Adaptive small-scale fisheries in the eastern Cantabrian coast through reliance on essential speciesBachiller, Eneko; Mugerza, Estanis; Murillas-Maza, Arantza; Mateo, Maria; Korta, Maria; Zarauz, Lucia
doi: 10.1093/icesjms/fsae132pmid: N/A
In recent decades, small-scale fisheries (SSF) activity along the Basque coast (eastern Cantabrian) has declined, which has led remaining vessels to undergo notable shifts in their targeted species and therefore the fishing gears used, aimed at enhancing efficiency. Within that context, this study combines logbooks and sales notes spanning from 1995 to 2022 to assess inter-annual and seasonal variations in fishing activity and the main target species across different fishing gears, namely ‘fleet segments’. Results reveal that the spring Atlantic mackerel (Scomber scombrus) and summer albacore (Thunnus alalunga) seasons, with an intensified harvesting under favourable conditions during the past decade, affected the activity of all other segments throughout the year. In the face of climate change affecting harvested species, a scenario where mackerel and/or albacore seasons are disturbed would lead the SSF to predominantly depend on European hake, mainly caught by declining longlines and set nets, as well as on complementary species. Assessing essential species targeted by each SSF segment relies on is crucial for stakeholders as it helps manage interactions between fleets targeting the same species (e.g. SSF vs. industrial and recreational fisheries), and understand gear shifts by vessels targeting specific species in certain seasons.
The influence of human and marine wildlife presence on white shark behaviour in nearshore areasMonteforte, Kim I; Butcher, Paul A; Morris, Stephen G; Tucker, James P; Griffin, Kingsley J; Kelaher, Brendan P
doi: 10.1093/icesjms/fsae146pmid: N/A
The co-occurrence of people and sharks within nearshore areas raises concerns about human safety. Unprovoked shark bites are one of the most renowned negative human–wildlife encounters. White sharks (Carcharodon carcharias) are implicated in most fatal unprovoked shark bites globally, but there is limited knowledge of white shark behaviour in the presence of people. We used drone-based methods to analyse human–shark and wildlife–shark interactions. We found a higher probability of a white shark interaction with a nearby person (0.81) in comparison to an animal (0.65). Fishers had the highest, and swimmers had the lowest probability of a white shark interaction. White sharks exhibited investigative behaviour in most interactions, with directional changes towards a nearby person or animal in 85.9% and 94.0% of interactions, respectively. There was a higher probability for white sharks to increase their speed towards animals (0.16) than people (0.01). The likelihood of white sharks altering their speed or direction when people were present depended on human activity. Overall, our study highlighted the value of drone technology in providing insights into white shark behaviour. It also supported the contention that, while people and white sharks coexist within nearshore areas, the probability of a negative human–wildlife encounter remains low.
Climate-driven changes in the timing of spawning and the availability of walleye pollock (Gadus chalcogrammus) to assessment surveys in the Gulf of AlaskaRogers, Lauren A; Monnahan, Cole C; Williams, Kresimir; Jones, Darin T; Dorn, Martin W
doi: 10.1093/icesjms/fsae005pmid: N/A
Climate-driven changes in the timing of spawning or migration can affect the availability of fish to surveys designed to monitor their abundance, complicating efforts to assess stock status and sustainably manage fisheries. From 2017 to 2019, trends in biomass estimates from four surveys used to monitor Gulf of Alaska pollock diverged. These conflicting trends increased uncertainty in the stock assessment and occurred during a time of rapid environmental change. We hypothesized that changes in spawn timing affected availability of pollock to a winter survey that targets pre-spawning aggregations. To test this, we reconstructed relative spawn timing using two independent data sources: spring larval surveys and observations of spawning state in mature female pollock. We found that changes in spawn timing relative to survey timing explained a significant portion of recent and historical discrepancies between survey and model estimates of biomass. We then incorporated measures of spawn timing/survey timing mismatch as catchability covariates in an enhanced state-space stock assessment model. Including spawn timing-based catchability covariates significantly improved the model fit to survey data and provided a mechanistic explanation for recent survey discrepancies.
A framework for multidisciplinary science observations from commercial shipsMacdonald, Alison M; Hiron, Luna; McRaven, Leah; Stolp, Laura; Strom, Kerry; Hudak, Rebecca; Smith, Shawn R; Hummon, Julia; Andres, Magdalena
doi: 10.1093/icesjms/fsae011pmid: N/A
Science Research on Commercial Ships (Science RoCS) is a grassroots multi-institution group of scientists, engineers, data managers, and administrators seeking to further research opportunities by equipping commercial vessels with suites of maritime appropriate scientific sensors operated autonomously on regular ship routes with minimal crew intervention. Science RoCS aims to foster cooperation between the shipping industry and scientific community at a level that will be transformative for societally relevant ocean science, promote cross-disciplinary ocean science through simultaneous observation of the air/sea interface and water column, and spur a technological revolution in observational oceanography by developing new turnkey, maritime-industry-appropriate scientific equipment whose data streams can be used to stimulate innovations in oceanic (physical, chemical, and biological) understanding and forecasting. We envision a future where scientific data collection on commercial ships is the new industry standard, providing repeat measurements in undersampled, remote regions, on scales not otherwise accessible to the scientific community.